TAKE a walk along the Seine in southeast Paris, about a mile east of Notre Dame Cathedral, and you’ll see a dense collection of boxy glass-and-steel office buildings, futuristic apartments, cleverly converted industrial structures, concrete mixers, forklifts and cranes. It’s what some consider a linchpin of Paris’s future: a huge development area on former industrial land and railway yards that could give a much-needed jolt to the city’s aging urban core.

Several prominent architects from France and other countries have had a hand in the project, whose building styles range from buttoned-up corporate to cutting-edge contemporary. Supporters laud the development, known as Paris Rive Gauche, as a futuristic alternative that could help revive the city’s economy and its struggling universities while creating much-needed housing.

But some in this always-opinionated city denounce it as a stale corporate wasteland. Not only does it lack neighborhood character, they say, but it is also gobbling up precious land that might be better devoted to parks, small shops and cultural spaces.

Either way it represents one of the last major zones for new development in a city whose boundaries, basically unchanged since the 19th century, have been filled to the limit.

The 321-acre project, in the making since 1990, brims with almost 100 office buildings, university facilities and apartment structures, about half completed. With its glassy new buildings and frenetic air of constant construction, the area seems more akin to Shanghai or some other city of cranes than the City of Light.

Most notably the goal is architectural variety. Unlike much of Paris, where buildings generally emulate one another on a given street, the area offers a broad mix of building styles. Although the various zones within the project must abide by height and massing regulations, there are relatively few design imperatives, and the master planning has been divvied among eight architects to ensure even greater diversity.

These include French architects like the Pritzker Prize winner Christian de Portzamparc, who planned the zone’s Masséna quarter; Paul Andreu, who mapped development on the Avenue de France, one of the site’s main commercial axes; and Bruno Fortier, who designed the Rue du Chevaleret, another major artery.

Gilles de Mont-Marin, deputy manager of Semapa, the development company overseeing the project, calls Paris Rive Gauche the most important development since Baron Haussmann transformed 19th-century Paris by carving out a network of broad avenues lined by blocks of mostly harmonious buildings. But there is a major difference, he says.

“We are not part of the Haussmannian fabric of Paris, and we think we have the right to have site-specific architecture,” he said. “The urban grid here is classical, but the architecture is exceptional.”

Whether this is the case is very much up for debate, but there are some striking results. Because Paris, with its dense historic center, is such a difficult place to win a design conmmission, the project is a huge opportunity, and most major French (and several international) architects have entered the fray by winning public competitions or signing on with developers. Among them are Norman Foster of Britain, Ricardo Bofill of Spain and luminous French names like Valode & Pistre, Chaix et Morel, Arte Charpentier, Jakob & MacFarlane, Rudy Ricciotti, Nicholas Michelin and Francis Soler.

Semapa, supervised jointly by the Paris city council and the French national railway, the S.N.C.F. (which owns about 80 percent of the land), has invested about $1.6 billion in infrastructure, subsequently selling land parcels to private and public entities. The project won city approval in 1991 after the city signed off on the construction of a large deck for development over the Gare d’Austerlitz station’s railyards and most of the mills and factories in the neighborhood had pulled out of town.

Divided into three zones — Austerlitz to the west, Tolbiac in the center and Masséna to the east — the development stretches from the Gare d’Austerlitz on its west end, to the Périphérique, Paris’s ring road, to the east. Completion is expected in about 10 years.

The newest buildings in the area, to the east, are generally the most adventurous, although some regard their grand gestures as overzealous at times. François Chochon’s Institut Jacques Monod, a biology research center for the University of Paris completed last year, consists of three slightly curved concrete structures, with unusually arranged horizontal window patterns, connected by a series of glass bridges along a lush raised courtyard. The street facades are fairly orthodox, but when viewed from the courtyard, their colored metallic elevations swoop dramatically.

Valode & Pistre’s new Center of Biotechnology Biopark involved renovating a 1980s building complex by covering it with dense undulating metallic trellises from which lush vegetation grows. A public housing project by the emerging firm Beckmann N’Thépé has a large “fault” at its center, allowing apartments more exposure to natural light. It narrows dramatically on its third floor, creating a raised courtyard between the building’s offset volumes. Portions of the building’s roof — largely covered with photovoltaic tiles to collect solar energy — are cut away to help provide daylight to small, slightly sunken rooftop gardens.

Spanning the Seine, and connecting the project to the Right Bank, is the Passerelle Simone de Beauvoir, a 1,000-foot-long steel bridge lined with oak planks by the Austrian architect Dietmar Feichtinger. Uninterrupted by pilings, it is designed in an intriguing figure-eight shape, a result of the intersection of its tensioned steel arch and convex suspension system.

Jean-Louis Cohen, a French architect and professor of architectural history at New York University, said he had been impressed by the project’s mixed uses and by its blend of architectural diversity and urban continuity, a goal that many believe has eluded developments with many big-name architects, like the plan for ground zero in New York.

Its contemporary aesthetic “gives the idea you can modernize Paris,” Mr. Cohen said.

Mr. Portzamparc said that while some Parisian urbanists were dismayed by the architectural variety, any attempt at classical harmony would be out of touch with the times. Like so many other world cities, he said, Paris is no longer homogeneous. “I sometimes say it is a zoo,” he said of the Masséna quarter. “A zoo can be interesting if you organize it well.”

Yet Axel Sowa, editor of the magazine Architecture d’Aujourd’hui, said he worried that the project had ignored the neighborhood that once existed here in favor of a large-scale urbanism: “formal, icy and not very convivial.”

Nonetheless a few buildings within Paris Rive Gauche literally draw from the past. In many instances old factory and mill buildings have been converted for university use. Mr. Ricciotti, winner of the French Grand Prix d’Architecture in 2006, transformed the colossal and surprisingly elegant 1921 Grand Moulins, or flour mills, with a mansard roof and neoclassical facade, into a library for the University of Paris 7. He painstakingly preserved most of the details, including the facade, concrete floors, beams and posts. Some floors were removed to open up the space, and metallic catwalks connect the building’s two main sections, which had been separated.

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Next door Mr. Michelin designed a contemporary glass-and-steel classroom building for the University of Paris 7 inside the very utilitarian, exposed concrete “Halle aux Farines,” the Grand Moulin’s flour storage site. The designer Frédéric Borel has transformed a red-brick factory that once produced compressed air cartridges into the lofty new Paris Val-de-Seine Architecture School and built a tall, quirky addition, composed of white and gray vertical interlocking cubes, lifted on stilts.

Such work has helped generate buzz, and attract people, to an area that some proclaimed half-dead when Dominique Perrault completed his National Library of France there in 1995. Dominique Alba, director of the Pavillon d’Arsenal, the city’s contemporary architecture museum, said it had finally become “a real place in Paris.”

Françoise N’Thépé, a principal at Beckmann N’Thépé, described the project as “quite a good response” to the city’s situation. “The inside of Paris is paralyzed now, so it’s very useful to imagine new ways to regenerate,” she said. All the same, she added, it’s “not very visionary.” Mr. de Mont-Marin predicts that Rive Gauche will compete with La Défense, the giant business district to the west of Paris, to attract businesses and will ultimately fare better because it is inside the city and offers both housing and office space, giving Parisians the ability to live where they work.

Both districts may prove vital for this office-poor city as it competes for business with nearby European capitals that are taking similar steps to modernize and grow. Semapa predicts that the development will eventually serve as many as 30,000 students, 60,000 office workers and 5,000 residents.

But many feel the project is a costly denigration of Paris’s elegant urban core, citing, for example, the unadventurous, profit-conscious corporate projects lining the much-maligned Avenue de France and surrounds.

Even Mr. Foster, known for admired structures like the diamond-latticed Hearst Tower in New York and the pickle-shaped Swiss Re building in London, toned down the design of his office building, simply called France Avenue, for the large French developer Sorif. Although it has innovative elements, like movable shutters and an off-center roof plane, it looks more or less like a commonplace glass office building.

Mr. Portzamparc admits that the commercial portion of his zone, developed for companies like Banque Populaire and Accenture, is denser than he had wished. He said that fierce demands for a monetary return on the developer’s big investment forced compromise.

“With an urban plan you have to deal with so many people: politicians, urban planners, users, promoters, investors, other architects, other engineers,” he said. “If you retain 60 percent of your goals it’s a very good thing.”

The most enthusiastic reviews have generally been reserved for the site’s publicly financed university and public housing projects, which by law were chosen in a competition.

Others complain that, like La Défense, the area lacks the street life and sidewalk-level charm for which Paris is loved. At the moment there are few cafes, restaurants or small shops to speak of. “It looks good on paper as a plan, but at an experience level it leads to the same old thing: well done, well detailed, just dry,” said Brendan MacFarlane of Jakob & MacFarlane, which is building a fashion institute inside an old warehouse. “We need something richer on an urban level.”

Mr. de Mont-Marin counters that the social life will arrive when more buildings are completed. At the project’s outset members of the French Green Party sought to limit the scale of construction. That battle resulted in compromises, yielding 25 acres of green space. The project also dealt with concerns about affordable housing, which will make up about 50 percent of residential space, according to Semapa.

Now most of the complaints come from artists, many of whom moved into the area, often as illegal squatters, when factories first started moving out in the 1970s, ’80s and ’90s. One of the only remaining artistic bastions is a collective known as Les Frigos, inside a large former refrigeration building in the middle of the site. The group has survived several close calls (including a plan to reduce the structure’s size and another to replace it with a cultural building). But longtime members like Jacques Rémus, a composer, are pessimistic.

“The average price per square meter for the Frigos is around 50 euros,” he said. “New buildings cost 450 euros per square meter here. The pressure against us is too great,” Mr. Rémus said.

Mr. de Mont-Marin of Semapa, who insists that Les Frigos are safe from eviction, seems unfazed by criticism of Paris Rive Gauche. He said he was pleased that it had come this far, especially after uncertainty at the beginning, when tenants were slow to move in.

Mr. Cohen of New York University said that while Paris Rive Gauche was “not a total success,” it helps fill a void in modern amenities in Paris while still honoring a tradition of density and urbanity.

“There are some very good buildings,” he said. “There are some dumb glass boxes. But overall the level of professionalism and detailing is good.”

He mused, “I might be able to live there.”

A version of this article appears in print on , on Page AR19 of the New York edition with the headline: Paris Gives Itself a Futuristic Transplant. Order Reprints|Today's Paper|Subscribe